Coaxial needle and severing snare

ABSTRACT

A device for treating a lesion comprises a sheath extending from a proximal end which, in an operative position, is located outside the body, to a distal end which, in the operative position is located within the body. A needle extending through the sheath has a tissue piercing distal tip and a central lumen extending through the needle from a proximal port to a distal opening formed in the distal tip and a needle actuator is provided for moving the needle between a retracted position in which the distal tip is received within the sheath to an injection position in which the distal tip extends distally beyond a distal end of the sheath. A snare extends within the lumen to a loop formed in a distal end of the snare and a snare actuator is provided for moving the snare between a covered position in which the loop is received within the lumen and an extended position in which the loop extends distally from the lumen beyond the distal tip.

This is a division of application Ser. No. 09/025,499, filed Feb. 18,1998, U.S. Pat. No. 5,961,526.

FIELD OF THE INVENTION

The present invention relates generally to the field of tissue ligation,and more particularly to an improved device and method for severinglesions.

BACKGROUND OF THE INVENTION

A wide variety of lesions, including internal hemorrhoids, polyps, andmucositis, may be treated by severing snare ligation.

In severing snare ligation, a targeted lesion is removed from thesurrounding tissue by an electrosurgical severing snare using radiofrequency (R/F) electric current to sever tissue or to achievehemostasis. A high radio frequency is used (i.e., above 100,000 Hz.) toavoid the potentially injurious stimulation of muscles and nerves whichresults from lower frequency R/F energy. Thus, electrosurgery istypically performed at frequencies of approximately 500,000 Hz.,although frequencies as high as 4,000,000 Hz. may be used.

Medical diathermy is similar to electrosurgery in that radio frequencycurrent is passed through the patient's body. The major differencebetween these two techniques is the density of the radio frequencyelectric current; the current density used in medical diathermy is keptlow to reduce tissue heating and to prevent necrosis.

There are three surgical effects that can be achieved withelectrosurgery. These include electrosurgical desiccation, which is alow power coagulation caused without sparking to the tissue;electrosurgical cutting, where electricity sparks to the targeted tissueand produces a cutting effect; and electrosurgical fulguration, whereelectricity sparks to the targeted tissue without causing significantcutting.

The above-described surgical effects can be accomplished by using eithera monopolar or bipolar output. For many applications, however, bipolaroutputs are preferable because the patient return electrode (necessaryin monopolar procedures and a common source of accidents) is eliminated,and any desiccation performed is extremely localized because, in a truebipolar operation, only the tissue that is grasped between the twoelectrodes is desiccated. Bipolar output, however, is less effective forcutting and fulgurating, and thus monopolar tools remain commonplace.Severing snares, for example, are almost all monopolar instruments.

In addition, three types of electrical current waveforms are typicallyused in electrosurgery. These include a “cutting” waveform, which cutstissue very cleanly but may cause the incised tissue to bleedexcessively; a “coagulating” waveform, which desiccates and fulguratestissue without significant cutting; and a “blended” waveform, which is acutting waveform that has a moderate hemostatic effect. A waveform's“Crest Factor” describes the degree of hemostasis that a waveform willproduce if properly applied.

To remove a lesion (or polyp) with an electrosurgical severing snare,the wire snare is looped around the targeted lesion and is tightened asthe snare is drawn into the sheath. The lesion is then desiccated andcut through electrosurgically. It is also possible to sever a lesion ina single step by cutting with a “blended” current. This allows a snareto cut through a lesion in one pass without having to worry aboutbleeding. Alternately, the lesion may be cut through mechanically with athin snare wire after the blood supply to the targeted tissue has beencoagulated and the tissue has been softened by a desiccation current.

Saline-Assisted Polypectomy (SAP), or “strip biopsy,” has become anincreasingly popular way of performing endoscopic mucosal resection(EMR) to diagnose and treat diseases of the gastrointestinal tract. Whenperforming SAP, a surgeon passes a needle through an endoscope andinserts the needle into the submucosa layer proximate to the lesion.Next, the surgeon injects physiological saline into the submucosa toelevate the lesion on a bed of saline solution. Once elevated, thesurgeon can easily remove the lesion by passing an electrosurgicalsevering snare over the lesion and ligating the lesion. SAP, however,typically requires the use of a large diameter double-channel endoscope,which is difficult to introduce into the patient and is hard tomanipulate. In addition, grasping forceps must be used to lift thelesion off of the layer of saline solution, which may result in a tearin the mucosa.

Accordingly, an alternate procedure has been developed called endoscopicaspiration mucosectomy (EAM). As described by Torii et al. in“Endoscopic Aspiration Mucosectomy as Curative Endoscopic Surgery,”Gastrointestinal Endoscopy, Vol. 42, No. 5 (1995), EAM can be used tolift up a targeted lesion with suction, rather than with forceps,thereby reducing the risk of injury to the mucosal surface. Whenperforming EAM, a double-channel endoscope is introduced into thepatient, the lesion is marked with a needle knife, and saline solutionor Glyceol™ (e.g., a hypertonic solution of 10% glycerol, 5% fructose,and physiological saline solution; available from Chugai PharmaceuticalCo., Tokyo, Japan) is injected into the submucosal layer beneath thelesion to separate the lesion from the layer. Next, the double-channelendoscope is withdrawn from the patient and a single-channel, videoendoscope equipped with a transparent aspiration cylinder is introducedinto the patient and (e.g., a Teflon® tube through which suction isapplied) an electrosurgical severing snare is tightened around the outercircumference of the cylinder.

Once the single-channel endoscope has been properly repositioned nearthe targeted lesion, the lesion and the surrounding mucosa are aspiratedinto the cylinder and the snare is pushed off the cylinder and tightenedaround the lesion to ligate the lesion. By first aspirating the lesioninto the tube before severing it, the lesion may be severed further downon the stalk than possible with SAP. After the targeted lesion has beensevered from the surrounding tissue, the severed tissue may remainaspirated into the cylinder to retrieve the sample for further study.Alternately, the severed tissue may be aspirated out of the cylinder topass through the body naturally.

However, while the EAM procedure described by Torii et al. may offercertain advantages over SAP, it still has its disadvantages. To performEAM, a surgeon must switch between a double-channel endoscope having aneedle knife and an injection needle (for marking the lesion andinjecting solution), and a more maneuverable single-channel endoscopehaving a severing snare and an aspiration cylinder(for ligating andaspirating the lesion) because the working channel of a single-channelendoscope cannot accommodate both an injection needle and a severingsnare simultaneously. Alternately, as discussed by Torii et al.,double-channel endoscopes are too large and are not desirable for theEAM procedure. Exchanging endoscopes, however, is time consuming-wastingsurgeons' time and prolonging the procedure.

U.S. Pat. No. 5,542,948 to Weaver et al. purports to disclose aninstrument in which a severing snare and an injection needle disposedside-by-side in separate lumens of the device are prevented from beingsimultaneously deployed by an actuator assembly which maintains one ofthe instruments (e.g., the severing snare) within the lumen until theother instrument (e.g., the injection needle) has been completelywithdrawn into its respective lumen.

This requires the use of a multi-lumen sheath including two lumens forcarrying the injection needle and severing snare. However, multi-lumensheaths take up valuable space and make the overall endoscopic apparatuslarge and bulky. The use of two lumens within a sheath also limits thesize of the severing snare and injection needle that can be used, as theinstruments are disposed through the sheath side-by-side.

In addition, the depth at which a surgeon using the apparatus disclosedby Weaver et al. may sever a lesion is limited because the device isdesigned to be used when performing SAP and does not, therefore, providefor an aspirating device. This prevents the use of the device of Weaveret al. in performing EAM.

SUMMARY OF THE INVENTION

The present invention is directed to a device for treating a lesionwithin a living body, comprising a sheath extending from a proximal endwhich, in an operative position, is located outside the body, to adistal end which, in the operative position is located within the body.A needle extending through the sheath defines a tissue piercing distaltip and a central lumen extends through the needle from a proximal portto a distal opening formed in the distal tip. A needle actuator isprovided for moving the needle between a retracted position in which thedistal tip is received within the sheath to an injection position inwhich the distal tip extends distally beyond a distal end of the sheathand a snare extends within the lumen to a loop formed in a distal end ofthe snare. A snare actuator is provided for moving the snare between acovered position in which the loop is received within the lumen and anextended position in which the loop extends distally from the lumenbeyond the distal tip.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more readily understood through the followingdetailed description, with reference to the accompanying drawings, inwhich:

FIG. 1A shows an apparatus according to a first embodiment of thepresent invention;

FIG. 1B illustrates an aspiration cylinder and a distal end of anendoscope;

FIG. 2 shows the apparatus according to the first embodiment with both aneedle handle and a snare handle fully-deployed;

FIG. 3 shows the apparatus according to the first embodiment with boththe needle handle and the snare handle partially-deployed;

FIG. 4 shows the apparatus according to the first embodiment with theneedle handle fully-deployed and the snare handle fully-retracted;

FIG. 5 shows the apparatus according to the first embodiment, arrangedas seen in FIG. 4, passing through an endoscope to which an aspirationcylinder has been coupled;

FIG. 6 shows the apparatus according to the first embodiment, arrangedas seen in FIG. 5, with the needle retracted and the snare extended andpressing against a lesion;

FIG. 7 shows an apparatus according to a second embodiment of theinvention, wherein the needle and the snare are located external to theworking channel of the endoscope, and the sheath is attached to theaspiration cylinder;

FIG. 8 shows the apparatus according to the first embodiment locatedadjacent to a targeted lesion;

FIG. 9 shows the apparatus according to the first embodiment with theneedle injecting a sclerotherapy agent between the mucosa and themuscularis propria;

FIG. 10 shows the apparatus according to the first embodiment with thesnare being maneuvered over the targeted lesion while the lesion and thesurrounding mucosa are aspirated through the inner diameter of the snareinto the aspiration cylinder;

FIG. 11 shows the apparatus according to the first embodiment with thesnare being pulled tightly around the targeted lesion;

FIG. 12 shows the apparatus according to the first embodiment with thetargeted lesion being ligating by the severing snare;

FIG. 13 shows the apparatus according to the first embodiment with thenow-severed lesion aspirated into the aspiration cylinder;

FIG. 14 shows a cross section of the apparatus of FIG. 1;

FIG. 15 shows the apparatus of FIG. 1A with the needle and the snare infully retracted positions;

FIG. 16 shows a cross-section of an additional embodiment of theinvention including a stop for limiting the movement of the snare andneedle; and

FIG. 17 shows a cross-section of a further embodiment including amechanism for latching the snare and needle together so that they may beretracted in unison.

DETAILED DESCRIPTION

As shown in FIG. 1A, an apparatus according to a first embodiment of theinvention comprises a sheath 1, having a proximal end 5 and a distal end10. A lumen 15 extends between the proximal and distal ends 5 and 10,and may preferably have a substantially circular cross-section. A distalaperture 20 is defined at the point where the lumen 15 exits the distalend 10 of the sheath 1.

The sheath 1 is designed to pass through the working channel 30 of anendoscope 25 as can be seen in FIG. 1B. The working channel 30 extendswithin the endoscope 25 from an accessible end (not shown) to a workingend 35 of the endoscope 25. The working channel 30 is sized to allow thefree passage of instruments therethrough from an opening formed in theaccessible end into the working channel 30 to the working end 35. Ofcourse those skilled in the art will understand that different scopeshave working channels 30 of various diameters and that it is necessaryonly to size the sheath 1 so that a sufficient clearance is preservedwithin the channel so that the sheath 1 may freely is pass through theworking channel 30. Of course, when the sheath 1 extends outside theendoscope 25, the size of the working channel 30 is not a factor indetermining the size of the sheath 1.

To configure the endoscope 35 for use with the apparatus according tothe invention, aspiration cylinder 40 is coupled to the working end 35of the endoscope 25. The aspiration cylinder 40, which may preferably beconstructed of a transparent bio-compatible plastic such as, forexample, polycarbonate or lexan, includes a distal end 45, which definesa distal aperture 50 and an aspirating chamber 55. The aspiratingchamber 55 is in communication with the working channel 30 of theendoscope 25 so that an instrument, such as that according to the firstembodiment of the present invention, may be passed through the workingchannel 30, through the aspirating chamber 55, and through the distalaperture 50 of the aspiration cylinder 40.

Endoscope 25 is preferably a single-channel endoscope. Alternately, thesurgeon may use a multiple-channel endoscope and use one or more of theother working channels for advancing an instrument, such as a forceps200 (shown in FIG. 7), basket, needle, or other device, through theendoscope 25, or for accommodating a fiber optical system (not shown).The length of the endoscope 25 should be sufficient to allow the surgeonto use the endoscope 25 and the attached aspiration cylinder 40 to reachthe targeted lesions within the patient's body.

An injection needle 60 is disposed through the lumen 15 of the sheath 1.The injection needle 60 defines a lumen 70, which terminates in a distalaperture 67, and has a proximal end (not shown) and a distal tip 65. Thecross-sections of the injection needle 60 and the lumen 70 arepreferably generally circular, and the cross-sectional diameter of theinjection needle 60 is less than the diameter of the lumen 15 of thesheath 1, through which the injection needle 60 passes. As thecross-sectional diameter of the injection needle 60 is less than thediameter of the lumen 15 of the sheath 1, the injection needle 60 isfree to move longitudinally through the lumen 15.

The proximal end of the injection needle 60 is connected to an injectionneedle handle 75, which slidably engages a handle body 100. Theinjection needle handle 75, which includes an injection port 77, may bemoved longitudinally along the handle body 100 from a fully-deployedposition (shown in FIG. 4), wherein the injection needle handle 75 hasbeen moved away from the distal end 105 (formed as a thumb handle 106)of the handle body 100, to a fully-retracted position (shown in FIG. 6),wherein the injection needle handle 75 has been moved proximate to thedistal end 105 of the handle body 100 relative to the fully-deployedposition. However, if the snare handle 90 is moved further proximally,the needle handle 75 may also be moved further proximally to furtherretract the needle 75. In the preferred embodiment of the invention, itis also contemplated that the injection needle handle 75 may bepositioned in any number of positions between the fully-deployed andfully-retracted positions.

Movement of the injection needle handle 75 controls and limits themovement of the injection needle 60 through the lumen 15 of the sheath1. When the injection needle handle 75 is in the fully-deployedposition, the distal tip 65 of the injection needle 60 extends throughand beyond the distal aperture 20 of the sheath 1 (as seen in FIGS. 2and 3). When the present invention is used with an endoscope 25 and aaspiration cylinder 40, the distal tip 65 of the injection needle 60will extend beyond the distal aperture 50 of the aspiration cylinder 40when the injection needle handle 75 is in the fully-deployed positionand the sheath 1 is properly positioned, either within the endoscope 25(as seen in FIG. 5) or outside the endoscope 25 (as seen in FIG. 7), forcarrying out the desired procedure. When the injection needle handle 75is in a mid-range (as seen in FIG. 3) or a fully-retracted position (asseen in FIG. 6), the distal tip 65 of the injection needle 60 iscompletely withdrawn within the lumen 15 of the sheath 1. By completelyretracting the injection needle 60 within the sheath 1 when theinjection needle 60 is not in use, a surgeon can substantially reducethe risk of accidental perforation or entanglement.

An electrosurgical severing snare 80 is disposed within the lumen 70 ofthe injection needle 60. The severing snare 80 has a proximal end (notshown) and a distal loop 85, which is flexible and made of light-gaugewire such as nitinol or stainless steel. The severing snare 80 ispreferably not surrounded by any insulating material so that, when r/fenergy is supplied to the severing snare 80, the injection needle 60 isalso “hot.” However, the sheath 1 is preferably formed as an insulatorto guard against short circuiting with an interior surface of theworking channel 30 and to protect tissue surrounding the lesion fromdamage prior to locating a final position and deploying a desired one ofthe needle 60 and the snare 80. Thus, the needle 60 may be used tocauterize bleeding vessels, or may serve as a point electrical surgeryknife.

The diameter of the severing snare 80, the cross-section of which ispreferably generally circular, is less than the diameter of the lumen 70of the injection needle 60, through which the severing snare 80 passes.Those skilled in the art will understand that, because two strands ofthe wire of the distal loop 85 or the severing snare 80 are receivedwithin the distal end of the lumen 70, it is preferable to select alight-gauge wire which is less than half the diameter of the lumen 70.As the cross-sectional diameter of the severing snare 80 is less thanthe diameter of the lumen 70, the severing snare 80 is free to movelongitudinally through the lumen 70. The proximal end of the severingsnare 80 is connected to a snare handle 90, which slidably engages thehandle body 100, and is in electrical communication with an R/F snareplug 95. Snare handle 90 may be moved longitudinally along the handlebody 100 between a fully-deployed position, (shown in FIGS. 2 and 3) inwhich the distal loop 85 extends from the distal end of the lumen 70,wherein the snare handle 90 is close to the distal end 105 of the handlebody 100, and a fully-retracted position (shown in FIG. 4), in which thedistal loop 85 is completely retracted into the lumen 70, wherein thesnare handle 90 is located adjacent to the thumb ring 106 of the handlebody 100. In the preferred embodiment of the invention, it is alsocontemplated that the snare handle 90 may be positioned in any number ofpositions between the fully-deployed and fully-retracted positions.

Movement of the snare handle 90 controls and limits the movement of thesevering snare 80 through the lumen 70 of the injection needle 60. Whenthe snare handle 90 is in the fully-deployed position, the distal loop85 of the severing snare 80 extends through and beyond the distalaperture 67 of the injection needle 60. When the present invention isused with an endoscope 25 and a aspiration cylinder 40, the distal loop85 of the severing snare 80 will extend beyond the distal aperture 50 ofthe aspiration cylinder 40 when the snare handle 90 is in thefully-deployed position, and the injection needle 60 and sheath 1 areproperly positioned, either within the endoscope 25 (as seen in FIG. 6)or outside the endoscope 25 (as seen in FIG. 6), for carrying out thedesired procedure.

When the snare handle 90 is in the fully-retracted position, the distalloop 85 of the severing snare 80 is completely withdrawn and collapsedwithin the lumen 70 of the injection needle 60. Of course, the loop 85will initially be compressed when it is drawn into the sheath 1 and, bydrawing the needle 60 proximally along with the snare loop 85, a usercan ensure that the snare loop 85 is collapsed by the sheath 1 beforebeing retracted into the lumen 70. By completely retracting the distalloop 85 and the severing snare 80 within the lumen 70, a surgeon cansubstantially reduce the risk of accidentally having another instrument,such as a forceps 200 (shown in FIG. 7) become entangled in the distalloop 85. The distal loop 85 of the severing snare 80 is also protectedfrom being accidentally perforated by the injection needle 60 by thefact that the distal loop 85 is located distal to the injection needle60.

For each of the above-described embodiments, when fully-extended and notdeformed by another object, the distal loop 85 defines a generallyelliptical area, which can be referred to as having a length 1 and awidth w. When the distal loop 85 is retracted into the lumen 70 of theinjection needle 60 (i.e., “collapsed”), width w is reduced toapproximately the diameter of the lumen 70. Accordingly, the areadefined by the distal loop 85 is substantially smaller after the distalloop 85 has been collapsed than before it has been collapsed. Distalloop 85 is able to be collapsed upon being retracted because the wirethat comprises the distal loop 85 is flexible. The distal loop 85 ispreferably biased so that, when the distal loop 85 is redeployed it willreturn to its precollapsed state and define roughly the same area as itdid before it was collapsed within the lumen 70. In addition as shown inFIGS. 11 and 12, the snare loop 85 may be biased so that, when outsidethe lumen 70, the loop 85 extends in a plane disposed at an angle, e.g.,90°, relative to the longitudinal axis of the needle 60. That is, theloop 85 may be biased so that, when deployed, it extends across anopening of the aspiration cylinder 40. This facilitates placement of theloop 85 over a lesion aspirated into the aspiration cylinder 40.

The R/F snare plug 95 is provided to transmit energy from an externalsource (not shown) to the distal loop 85 of the severing snare 80.

In the preferred embodiment of the invention, the sheath 1 is designedto pass through the working channel 30 of the endoscope 25. By using thedevice in this manner, the overall cross-sectional area of the endoscopeis not increased due to the presence of the sheath 1, injection needle60, and severing snare 85, although the aspiration cylinder 40 mayslightly increase the profile of the endoscope 25. Furthermore, becausethe severing snare 80 is coaxial with the injection needle 60, thecombination of the two instruments takes up approximately the sameamount of room within the working channel 30 that a standard injectionneedle would.

If, however, the injection needle 60 and the severing snare 80 werepositioned side-by-side and electrically isolated from one another byseparate sheaths, the combination of the two instruments would requiremore room within the working channel 30, thereby necessitating the useby the surgeon of a large endoscope or the elimination of the advantagesof having both instruments simultaneously present at the site of thelesion and, instead, having to perform several “exchanges” as discussedin the prior art.

Thus, a surgeon using the present device may use an endoscope with arelatively small working channel 30 while still enjoying the benefits oflocating both an injection needle 60 and a severing snare 80simultaneously at the site of a lesion. Alternately, the surgeon may useany “free space” within an larger diameter endoscope (such as thediameter that would be needed if the two instruments were positionedside-by-side) for passing other instruments, such as a forceps 200,through the working channel 30. Also, the surgeon could select aninjection needle 60 and a severing snare 80 having slightly largerdiameters, thereby allowing for more injection flow through theinjection needle 60 and for a stronger severing snare 80.

In an alternate embodiment as shown in FIG. 7, the sheath 1 may belocated external to the working channel 30 of a relatively smalldiameter endoscope 25. In such a configuration, a portion of the sheath1 is attached to the aspiration cylinder 40 by tape, cable ties, or meshmeans (not shown). While this configuration enlarges the overall profileof the endoscope 25 and aspiration cylinder 40 assembly, the surgeon isthen free to use another instrument, such as a forceps 200, basket,needle, or cautery device, through the working channel 30 of theendoscope 25, without having to first remove the injection needle 60 andthe severing snare 80 from the patient. The open working channel 30 ofthe endoscope 25 also allows for multiple combinations of instruments tobe used within the working channel 30 without having to remove theendoscope 25 from the body of the patient.

A novel method for ligating a lesion will now be described withreference to FIGS. 8-13.

First, a surgeon administers a local pharyngeal anesthesia or generalanesthesia to the patient and introduces into the patient an endoscope25 having an aspiration cylinder 40 coupled thereto. The surgeon thenpasses the sheath 1 through the working channel 30 of the endoscope 25with the sheath 1 protecting the endoscope from being scraped or damagedby the needle as it is passed through the working channel 30. A needle60 is passed through the lumen 15 of the sheath 1 with a severing snare80 disposed within the lumen 70 of the needle 60. Alternately, thesurgeon may forgo use of a aspiration cylinder 40 and may attach thesheath 1 to the outside of the endoscope 25.

As shown in FIG. 8, the surgeon positions the distal end of theaspiration cylinder 40 adjacent to the lesion 205 that the surgeonwishes to remove. The lesion 205 as shown in FIGS. 8-13 is illustrativeof a lesion found in the gastrointestinal tract and may, for example, beassociated with early gastric cancer or adenoma. The lesion 205 is partof the mucosa 210, and is positioned over a submucosa layer 215 (themuscularis propria).

Next, the surgeon passes an injection needle 60 (shown in FIG. 9)through the mucosa 210, and injects a sclerotherapy agent L or salinesolution between the mucosa 210 and the muscularis propria 215, therebyseparating the mucosa 210 from the muscularis propria 215. It ispreferable that a sclerotherapy agent L, such as Glyceol™, be usedrather than saline solution because the bulge formed between the mucosa210 and muscularis propria 215 lasts longer when a sclerotherapy agentis used.

Once the lesion 205 has been elevated on a bed of sclerotherapy agent L,the surgeon deploys the snare 80 and positions the loop 85 around thelesion 205 and then aspirates the lesion 205 through the loop 85 intothe aspirating chamber 55 of the aspiration cylinder 40 (shown in FIG.10) and tightens the loop 85 around the tissue to sever the lesion 205(shown in FIG. 12).

If the surgeon is using an electrosurgical severing snare, as describedin the background of the invention, he would apply the appropriate R/Fenergy (i.e., “cutting,” “coagulating,” or “blended”) to the snarethrough an R/F snare plug 95 while severing the lesion 205. As shown inFIG. 13, after the lesion 205 has been severed, it may be retained inthe aspiration cylinder 40 to be removed from the body for furtherpathology study or aspirated out of the aspirating chamber 55 to passthrough the body. If the lesion 205 is aspirated out of the aspirationcylinder 40, the surgeon may immediately proceed to treat a subsequentlesion (not shown) without having to remove the endoscope 25 and theaspiration cylinder 40 from the body.

Alternately, the surgeon may pass an instrument, such as a forceps 200,through the working channel 30 or an external or an addition lumen (notshown) of the endoscope 25 to grasp and retrieve the lesion 205. If thesheath 1 occupies the working channel 30 and no other lumen is provided,then the surgeon could exchange sheath 1 for the desired instrument 200,or attempt to pass the instrument 200 around the sheath 1 within theworking channel 30. This exchange would be eliminated, however, if thesheath 1 were connected to the outside of the aspiration cylinder 40 (asseen in FIG. 7), thereby freeing up the working channel 30 of theendoscope 25 for other instruments, such as the forceps 200.

In addition, if the surgeon opts not to perform EAM and instead electsfor SAP, the forceps 200, rather than suction, would be used to separatethe lesion 205 and the mucosa 210 from the muscularis propria 215.Accordingly, it would be desirable to adapt the present invention toallow for both the coaxial needle 60/severing snare 80 instrument andthe forceps 200 to be simultaneously located at the site of the lesion205. In accordance with an alternate embodiment of the presentinvention, the sheath 1 could be located external to the endoscope 25,thereby still allowing the surgeon to use a single-channel (rather thana double-channel) endoscope 25 to perform the SAP procedure.

Those skilled in the art will understand that the injection needlehandle 75 is preferably coupled to the severing snare handle 90 so that,when the severing snare 80 is retracted, the injection needle 60 is alsoretracted at least until the distal tip 65 of the injection needle 60 isreceived within the sheath 1. For example, after grasping tissue, thediameter of the distal loop 85 will be expanded to surround the tissueand, when the snare 80 is retracted while the injection needle 60 isfully or partially deployed, the expanded loop 85 will be too large toenter the injection needle 60. Thus, the needle 60 will be pushedproximally by the proximal travel of the distal loop 85 until thesevering loop 85 comes into contact with the distal end 10 of the sheath1. As shown in FIG. 14, as the snare 80 is drawn further into the sheath1, decreasing the diameter of the distal loop 85, there is no impedimentto the proximal travel of the needle 60 which is pushed furtherproximally into the housing 100. FIG. 15 shows the apparatus of FIG. 14in which no stop 110 is provided to limit the proximal travel of theneedle 60, wherein both the snare 80 and the needle 60 are completelywithdrawn into the sheath 1.

FIG. 16 shows a further embodiment of the apparatus according to thepresent invention in which a mechanism is provided to control the motionof the needle 60 and the snare 80. Specifically, the apparatus of FIG.16 includes a stop 110 formed as a rod extending across the interiorlumen of the handle body 100 preferably substantially perpendicular to alongitudinal axis of the handle body 100. The stop 110 contacts thesnare handle 90 to define the distal-most position of the snare handle90 and, consequently, the distal-most position of the snare 80.Similarly, the stop 110 contacts the needle handle 75 to define theproximal-most position of the needle handle 75 and, consequently, of theneedle 60. Those skilled in the art will understand that the rod 110 maybe formed as a separate piece bonded to, or molded into, the interior ofthe handle body 100. In addition, an increased diameter portion 112 ofthe needle 60 is provided to further define the proximal and distallimits of travel of the needle 60. Specifically, the proximal end 114 ofthe increased diameter portion 112, which is formed as a seal to sealthe interior lumen 70 of the needle 60, facilitates contact between thestop 110 and the needle 60 and includes a receiving cavity 113 to ensurethat the needle 60 does not travel proximally past the stop 110. Adistal end 116 of the increased diameter portion 112 abuts a shoulderformed on a distal end of the handle body 100 when the needle 60 is in adistal-most position. In addition, when the needle actuator 75 isretracted to the proximal-most position, it can be rotated about thelongitudinal axis of the housing 100 so that the needle actuator 75 islocked into a locking bay 118.

FIG. 17 shows a device similar to that of FIG. 16 except that theincreased diameter portion 112 of the needle 60 includes a detente 120extending from the proximal end 114. This detente 120 cooperates with alatch 122 formed on a portion of the snare handle 90 extending withinthe housing 100 so that as the snare 80 is pushed distally, the latch122 will abut the proximal end 114 of the increased diameter portion 112pushing the needle 60 out to the fully deployed position. of course, theneedle 60 may be independently deployed by moving the needle handle 75distally. In any case, when the needle 60 reaches the fully deployedposition and the distal end 116 abuts the shoulder formed on the distalend of the handle body 100, the latch 122 moves underneath the detente120 and locks the snare handle 90 to the needle 60. Thus, when the snare80 is withdrawn proximally, the needle 60 is also drawn back into thesheath 1 until further proximal travel of the needle 60 is stopped bycontact between the distal end 114 and the stop 110 at which point thelatch 122 is released from the detente 114 and the snare 80 is retractedinto the interior lumen 70 of the needle 60.

Still other objects and advantages of the present invention will becomereadily apparent to those skilled in this art from the above-reciteddetailed description, wherein the preferred embodiment of the inventionhas been shown and described.

The description of the preferred embodiment is simply by way ofillustration of the best mode contemplated for carrying out theinvention. As will be realized, the invention is capable of other anddifferent embodiments, and its several details are capable ofmodification in various respects, all without departing from theinvention. Accordingly, the drawings and descriptions are to be regardedas illustrative in nature, and not as restrictive.

What we claim is:
 1. A lesion treating system comprising: an endoscopedefining a working channel extending therethrough; a sheath disposedwithin the working channel of the endoscope so that a distal end of thesheath is located adjacent to a distal end of the working channel; afluid injection needle having a tissue piercing tip at a distal endthereof and a fluid injection port at a proximal end thereof, the fluidinjection needle extending through the sheath, the fluid injectionneedle defining a central lumen which extends from the fluid injectionport to the tissue piercing tip; and a snare extending through thecentral lumen, the snare having a loop formed at a distal end thereof.2. The system according to claim 1, further comprising an aspirationhousing connected to a distal end of the endoscope.
 3. The systemaccording to claim 2, wherein the sheath extends into the aspirationhousing and wherein the fluid injection needle and the snare may beextended into and retracted from the aspiration housing.
 4. The systemaccording to claim 1, wherein the snare comprises an electricallyconductive material and wherein a proximal end of the snare is coupledto a contact for coupling the snare to a source of R/F energy.
 5. Amethod for severing a portion of tissue comprising the steps of:inserting into a body an endoscope defining a working channel extendingtherethrough, wherein a sheath is disposed within the working channel ofthe endoscope so that a distal end of the sheath is located adjacent toa distal end of the working channel and wherein a fluid injectionneedle, having a tissue piercing tip at a distal end thereof and havinga fluid injection port at a proximal end thereof and which defines acentral lumen which extends from the fluid injection port to the tissuepiercing tip, extends through the sheath and further wherein a snarehaving a loop formed at a distal end thereof extends through the centrallumen; positioning the endoscope adjacent to a portion of tissue to besevered; and performing one of the steps of: extending the fluidinjection needle from a distal end of the endoscope to penetrate thetissue to be severed to inject fluid into the tissue; and extending thesnare from the distal end of the endoscope to encircle and sever thetissue to be severed.
 6. The method according to claim 5, wherein thestep of extending the fluid injection needle from the distal end of theendoscope to penetrate the tissue to be severed to inject fluid into thetissue is performed and then the step of extending the snare from thedistal end of the endoscope to encircle and sever the tissue isperformed.
 7. The method according to claim 5, further comprising thestep of drawing the portion of tissue to be severed into a chamberformed at the distal end of the endoscope, wherein the drawing step isperformed after the step of extending the fluid injection needle fromthe distal end of the endoscope to penetrate the tissue to be severed toinject fluid into the tissue.
 8. The method according to claim 5,further comprising the step of drawing the portion of tissue to besevered into a chamber formed at the distal end of the endoscope,wherein the drawing step is performed prior to the step of extending thesnare from the distal end of the endoscope to encircle and sever thetissue to be severed.
 9. The method according to claim 5, wherein thefluid injected into the tissue is a sclerotherapy agent.
 10. The systemaccording to claim 1, further comprising: a needle actuator for movingthe fluid injection between a retracted position in which the tissuepiercing tip is received within the sheath and an injection position inwhich the tisue piercing tip extends distally beyond the distal end ofthe sheathl and a snare actuator for moving the snare between a coveredposition in which the loop is received within the central lumen and anextended position in which the loop extends distally from the centrallumen beyond the tissue piercing tip.
 11. The system according to claim10, wherein the needle actuator is coupled to the snare actuator sothat, as the snare actuator is moved from the extended position to thecovered position while the needle is in the injection position, theneedle is moved from the injection position to the retracted position.12. The system according to claim 10, further comprising a handlecoupled to a proximal end of the sheath, wherein the snare actuator andthe needle actuator are coupled to the handle.
 13. The system accordingto claim 12, wherein the handle includes a snare locking mechanism forlocking the snare actuator in a desired position wherein the desiredposition may be one of the covered position, the extended position andany position intermediate between the covered and extended positions.14. The system according to claim 12, wherein the handle includes aneedle locking mechanism for locking the needle actuator in a desiredposition wherein the desired position may be one of the retractedposition, the injection position and any position intermediate betweenthe retracted and injection positions.